Everything running very hot

Discussion in 'Getting Started' started by jmil, Apr 30, 2020.

  1. jmil

    jmil Member

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    I've appreciated everyone's contributions to these forums. It's helped me get my printer built and to the point it's operational. I've completed the steps up to printing the Benchy model successfully. The issue I've encountered is I'm getting driver temperature warnings through Duet and my stepper motors are getting very hot. I created a larger file to print and it started successfully but then stopped extruding about half way. In checking it out it appears the extruder motor got so hot that it softened the PLA filament and stopped extruding. I haven't had to debug motor issues in the past so would appreciate any hints on where to start looking. I should also mention the printer is in my garage in Phoenix, AZ so the temperatures are up to about 90 degrees Fahrenheit. Wasn't worried since my other printers run just fine and seem to like the heat.
     
  2. ByteSized

    ByteSized Member

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    Check your stepper motor current (M906 in config.g), usual recommendation is to run them at about 85% of rated current to avoid them running too hot.
     
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  3. Spoon Unit

    Spoon Unit Well-Known Member

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    The key thing is to to give you drivers enough juice so they don't miss steps. More than that and you're just generating heat. Here's my setup for currents:

    Code:
    M906 X1200 Y1200 Z1330 C500 E1200:1200:1200:800 I30   ; Set moto currents (mA) and motor idle factor in percent
    Nothing feels hot to the touch. Z looks high, but it doesn't move much. I might look to lower that as I've only just noticed it's set this high.
     
  4. ByteSized

    ByteSized Member

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    At 85% my X, Y & E motors run about 45 - 55C during a long print (I think they are usually rated for max 70 or 80C).

    If you lower the max motor current then you may need to increase the current used during homing (homex.g etc), eg:

    Code:
    M913 X25 Y25             ; drop motor currents to 25%
    This is what I think the motors are:

    Code:
    Z axis
        Not certain as I didn't want to disassemble my Z axis to check, but I think it's this:
        https://e3d-online.com/leadscrew-motor-with-pom-nut
        34mm body
        1.8 step angle
        1.33A / phase
        2.8V
        3.2Kg/cm holding torque
    
    X and Y
        Moons Stepping Motor
        MS17HD294200
        https://www.moonsindustries.com/p/nema-17-standard-hybrid-stepper-motors/ms17hd2p4200-000004611110008901
        39.8mm body
        1.8 degree step
        Rated current 2A
        0.48 Nm holding torque
        0.28Kg motor weight
      
    TC motor (C)
        https://e3d-online.com/catalog/product/view/id/9357/s/toolhead-stepper-motor/
        400mA / phase
        70C max operating temp
    
    Titan motor
        https://e3d-online.dozuki.com/Item/Compact_but_powerful_motor
        40mm body
        0.9 step angle
        1.68A / phase
        2.8V
        3.5Kg/cm holding torque
        0.28Kg weight
    
    
    Motor        Rated current   85%
    Z            1.33            1.13
    X & Y        2.00            1.70
    Tool Changer 0.40            0.34
    Titan        1.68            1.42
    
    
    Which gives me this:

    Code:
    M906 X1700 Y1700 Z1130 C400 E1420:1420:1420:1420 I30     ; Set motor currents (mA) and motor idle factor in percent
     
    #4 ByteSized, May 4, 2020
    Last edited: May 4, 2020
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  5. Nibbels

    Nibbels Well-Known Member

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    About the C-Stepper.

    I really need force if I want to lock some of my tools - otherwise I experienced loosing steps sometimes. Even with fat/lubricant.
    On my TC 0.34A would never work reliable.

    So I switch up the current to 600mA for those 2 seconds:
    upload_2020-5-4_23-1-38.png
    Then my lock and unlocking is reliable.
     
  6. Spoon Unit

    Spoon Unit Well-Known Member

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    So, you keep at 400mA when it's doing nothing? And then move it to 600mA before it moves? :)
     
  7. ByteSized

    ByteSized Member

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    I bet he could get away with dropping it a bit lower while it's doing nothing.;)
     
  8. Nibbels

    Nibbels Well-Known Member

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    Only when the lock and unlock macro runs I need more torque.
    In theory
    - The stepper needs to stretch the spring (at most when moving one direction),
    - We have some friction losses while moving
    - Maybe some displacement losses of dirt and fat

    I guess there is not much torque needed to hold the pin in place.

    So yes. I bump up the current for just ~2 seconds. Like shown in the picture atop.
    The motor has no time to heat up, it wont burn that fast, the magnets will probably never see too much heat.

    It is not that it wont work at 400mA but after ~12 prints it failed once. So I had to do something.
    The alternative would have been to get a precisely milled version of the tool dock adapter. My printed versions are a bit weak and probably at a tiny angle or tenth of a millimeter off. If I could adjust that perfectly, I would have to manage less torque.

    Ah yes, I had the plan to have an even lower current when the C Stepper is idling and only holding the pin in place. But I forgot to follow this path.
    Thanks for the reminder.


    Another thing is, that formerly the sensorless homing of my C Stepper worked perfectly. Rightnow It failes most of the time. I dont know what changed. I will have to look at this within the next weeks again:
    upload_2020-5-5_0-46-57.png
    Homing works, but I end up using this fallback.
     
  9. Spoon Unit

    Spoon Unit Well-Known Member

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    I was thinking more along the lines of keeping at 600mA all the time, given that it's doing nothing much and therefore probably not pulling much. I never even considered it needing some power to stay still, so now I'm feeling a bit daft. So, if it's set to XmA, will it always pull X even if stationary?
     
  10. ByteSized

    ByteSized Member

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    Joking aside, 340mA (85%) didn't reliably lock for me either, but so far 400mA has been reliable. I wasn't comfortable leaving the setting permanently above 100% if I could avoid it, so @Nibbels solution seems a good idea if I ever have locking problems.


    Current is governed by the stepper driver, to maintain full holding torque I think the coils must be energised with XmA at all times. However we've all experienced that a slow moving or stationary motor (like Z) runs cooler than a more active motor, I've not thought about all the reasons for that but it may be due to inductance in the coils causing increased resistance each time the coil energises. If that's the case it's "probably" perfectly safe to run C a little over its rated current (which is probably why the default config my machine came with had C500).
     
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  11. jmil

    jmil Member

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    Thanks for the suggestions. I took off the back cover, dropped the currents and put a small fan blowing on the back and was able to finish a three hour print with no issue. X and Y stayed at about 40 C, the extruder ran at about 43 C. The stepper driver chips ran at about 40 C as well. I'll try another print with just the reduced currents and see if the other steps are needed. My laser temp reader is coming in handy.
     
  12. dc42

    dc42 Well-Known Member

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    On Duet 2, I recommend you reduce the current below 600mA when it's not doing anything, because the rated current of the motor is only 400mA RMS.

    If using Duet 3 you can leave it at 600mA and use M917 to reduce the standstill current factor.
     
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  13. Spoon Unit

    Spoon Unit Well-Known Member

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    OK. Good input. I think I'll reduce mine to 400 default then, and then I'll just leave it there. It was set to 500 as a result of original config.g given. I should have looked it up really. Thanks for the input.
     

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